This invention relates generally to automatic liquid dispensing apparatus, and more particularly to apparatus for automatically dispensing a desired amount of gasoline from a service station gasoline pump.
Owing to the increased cost of gasoline and the difficulty in obtaining competent labor for operating service stations, there has developed an interest in providing fully or semi-automatic gasoline pumping systems that can easily be operated by the customer, or a number of which can simultaneously be operated by a single attendant. For a number of years it has been common to equip gasoline pumps with hose nozzles having means for sensing a full tank in the vehicle and shutting off in response thereto. However, large numbers of customers still prefer to purchase gasoline in specific dollar or gallon amounts, and the aforementioned automatic cut-off pumps are of no benefit in such cases.
The emphasis has thereby turned to automatic pumps which respond to a selected quantity of gasoline, indicated in dollars or gallons. The prior art is replete with many such systems, but they have for the most part been complex, costly, and unreliable. Many utilize complicated electrical systems, which are undesirable on a gasoline pump from the standpoint of maintenance and fire safety. Others have been pneumatically operated, but they have been complex, also. If a system is unreliable and cannot be trusted by the operator, it is less useful than a completely manual system. High maintenance costs cannot be tolerated in the service station business. Finally, the prior art systems cannot easily be installed in existing gasoline pumping systems, and therefore to place them into service would involve a complete equipment change-over at the service station level, which would be a very costly undertaking.